I've been involved professionally in business advisory matters, and I would always suggest to anyone starting a new business not to undervalue their skills in working out their charges (assuming, of course, they are capable of doing a good job!).

Just because you enjoy the work, perhaps as an extension and contribution to your hobby, remember that, if you really are good, you will hopefully get further work by recommendation, most especially if your prices are "cheap". And it is then very difficult to increase those prices if you have pitched them too low.....

Also a professional photographer (as any business) will need to factor into his prices all the overheads of a business....rent, lighting and heating of premises,
office costs, amortisation of equipment, etc., etc., which are all there and have to be paid for before a single photo is sold...